How many countries agreed to stop using coal?

The annual climate conference* took place in Bonn, Germany, during November 6 and 17 to talk about how to stop ongoing climate change. Using coal for electricity generation is considered one of the main causes of climate change.

Photo) Coal-fired plants burn coal to generate electricity

During the conference, 15 countries** joined an anti-coal team and announced that they would stop using coal. Those countries try to increase the number of team countries to 50 countries by the next 2018 conference.

Which fraction shows the ratio of the current team countries and the targeted team countries.